A phenolic resin foam board is generally produced by a method in which a foamable phenolic resin composition composed of a phenolic resin, a foaming agent, a curing catalyst, and the like (hereinafter sometimes simply referred to as a “foamable resin composition”), is kneaded by a dynamic mixer having a rotor blade and the like, the resultant mixture is ejected onto a surface material traveling at a constant speed, and then formed into a sheet between conveyors in a curing furnace. For example, as a method of using multiple ejection nozzles, a method of supplying a phenolic resin composition onto a surface material in a linear belt shape at predetermined intervals with multiple grooves (Patent Literature 1) is used.